Fluid End Assembly for Delivery of Fracture Fluid

ABSTRACT

A fluid end for a high-pressure pump with a plurality of horizontal plunger bores that have an open end and a closed end for receiving a reciprocating plunger at its open end. The fluid end is provided with a corresponding number of vertical suction bores, each of which intersect one of the horizontal plunger bores and contains a valve seat below the plunger bore and a valve seat above the plunger bore. A suction manifold is fixedly attached to the bottom of the fluid end to provide a flow of fluid into the fluid end via the vertical suction bores. A high-pressure discharge bore intersects the vertical suction bore and receives fluid pressurized by the plungers via upper valves.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Nos. 63/268,770, 63/268,772 filed Mar. 2, 2022, which are both incorporated herein by reference. This application is filed concurrently with U.S. application Ser. No. 18/116,247, entitled “Method for Removal of Valve Seats within Fluid End Assembly,” which is also incorporated herein by reference.

FIELD OF THE DISCLOSURE

The subject matter of the present disclosure relates to fluid delivery systems, and in particular to a fluid end pump for delivery of fluids under high pressure.

BACKGROUND OF THE DISCLOSURE

A current challenge that faces oil companies is to produce oil and gas in an economic manner from low permeability reservoir rocks. Production rates can be increased by resorting to hydraulic fracturing, a technique that increases rock permeability by creating cracks in the reservoir rock so that hydrocarbons can flow into the well freely. During a hydraulic fracturing operation, a slurry of proppant and fluid is pumped into the earth under very high pressure. The slurry enters the reservoir rock and fractures it. Proppants are carried in suspension by the fluid into the fractures. When the pressure is released from the well, the fractures partially close onto the proppants, which in turn leaves cracks in the rock for oil and gas to migrate into the well.

Fluid pumps, such as well-service pumps (WSP), are used to develop the pressures necessary to complete the fracturing operation. These pumps include a power end and a fluid end and can pump fluid at higher pressures than a mud pump. A portion of a well-service pump 10 is shown in FIG. 1A. In this example, the well service pump 10 is a quintiplex well service pump, although triplex well service pumps are also used. The pump 10 has a power assembly 12, a crosshead assembly 16, and a fluid assembly or fluid end 40. A gear reducer 14 on one side of the pump 10 connects a drive (not shown) to the power assembly 12 to drive the pump 10.

As shown in the cross-section of FIG. 1B, the pump's power assembly 12 has a crankshaft 20 supported by bearings in the power assembly 12. Crankpins are offset from the crankshaft 20's axis of rotation and convert the rotation of the crankshaft 20 into a reciprocating motion to operate pistons or plungers 30 in the pump's fluid end 40. An end of the crankshaft 20 extends outside the power assembly 12 for coupling to the gear reducer (14; FIG. 1A) and other drive components.

Connecting rods 22 connect from the crankpins on the crankshaft 60 to the pistons or plungers 30 via the crosshead assembly 16. In a typical connection, the connecting rod 22 connects from a crankpin on the crankshaft 20 to a wrist pin 24 on a crosshead 18. The wrist pin 24 allows the connecting rod 20 to pivot with respect to the crosshead 18, which in turn is connected to the pistons or plunger 30.

During operation, an electric motor or an internal combustion engine (such as a diesel engine) drives the pump 10 by the gear reducer 14. As the crankshaft 20 turns, the crankpins reciprocate the connecting rods 22. Moved by the rods 22, the crossheads 18 reciprocate inside fixed cylinders. In turn, the plungers 30 coupled to the crossheads 18 also reciprocate between suction and power strokes in the fluid end 40. Withdrawal of the plunger 20 during a suction stroke pulls fluid into the fluid end 40 through an input valve 60 a connected to an inlet 44. Subsequently pushed during the power stroke, the plunger 30 then forces the fluid under pressure out through the output valve 60 b connected to an outlet 48 on the fluid end 40.

In this way, the fluid end 40 uses the reciprocating plungers 30 to displace the fluid to produce high pressures. The valves 60 a-b control the fluid flow from the suction inlet 44 to the high-pressure discharge outlet 48.

Details of a fluid end 40 are shown in further detail in the cross-sectional view of FIG. 2 . The fluid end 40 has a body 41 having intersecting cross-bores 42, 43. To facilitate manufacture, a plunger bore 43 is formed horizontally through the body 41 and extends from one side to the other, and a fluid bore 42 is formed vertically through the body 41 and extends between top and bottom of the body 41. A fluid area 45 is formed at the intersection of the two bores 42, 43. The plunger 30 is inserted in one end of the plunger bore 43 and can be reciprocated back and forth as noted above. A seal arrangement 32 seals the plunger 30 in the plunger bore 43. The other end of the plunger bore 43 has an opening 47, which is sealed by a side closure (e.g., suction cover) 50 a having a sand cap or cover 52 and a retainer or nut 54.

Meanwhile, the fluid bore 42 has an inlet 44 on the bottom of the body 41, and an inlet valve 60 a at the inlet 44 controls fluid communication between the inlet 44 and the fluid bore 42. To facilitate manufacture, the fluid bore 42 has an opening 46 at the top of the body 41, and a closure (e.g., discharge cover) 50 b having a sand cap 52 and a retainer or nut 54 seals the opening 46. An outlet or side port 48 in the body 41 communicates with the fluid bore 42, and an outlet valve 60 b installed in the fluid bore 42 controls fluid communication between the outlet 48 and the fluid bore 42. As shown, the valves 60 a-b can be check or poppet valves having a seat, a poppet, and a spring.

During operation, the plunger 30 reciprocates back and forth within the plunger bore 43. When the plunger 30 is moving away from the sand cap 52 of the side closure 50 a, the input valve 60 a opens and fluid is drawn into the fluid area 45 through suction inlet 44. Meanwhile, the output valve 46 is drawn into its upper valve seat and is closed. During this state, the high-pressure outlet 48 cannot communicate with the suction bore 42.

As plunger 30 is then pushed towards plunger bore sand cap 52, displacing the fluid under high pressure, the inlet valve 60 a closes, and the conventional plunger bore 43 cannot communicate with the suction inlet 44. However, the outlet valve 60 b is opened to allow the fluid in the fluid area 45 to travel to high pressure outlet 48.

As noted above, the sand cap 52 and nut 54 are installed in the opposite opening 47 of the plunger bore 43 that receives the plunger 30. The sand cap 52 and nut 54 can be removed to provide access to the internal components for servicing. Unfortunately, the thread between the nut 54 and the opening 47 tends to weaken under the high cyclic pressure as the plunger 30 reciprocates and displaces fluid. For this reason, the working pressure of the conventional fluid end 40 needs to be limited to avoid cyclic fatigue.

As shown in the further detail of FIG. 3 , during the displacement of the fluid, cyclic pressure force F1 is focused on the side closure 50 a in the conventional fluid end 40. The force F1 pushes the sand cap 52 towards the nut 54. This creates very high stress on threads between the nut 54 and opening 47 and in turn creates cyclic pressure force F2 on the fluid end 40.

During high pressure operation, the fluid end 40 may crack at the end face 49 radially around opening 47. The threads between the nut 54 and opening 47 may fail and strip or stretch. The damage in turn causes costly down time. Once these types of failures occur, the conventional fluid end 40 cannot be repaired and is damaged beyond repair.

The subject matter of the present disclosure is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.

SUMMARY OF THE DISCLOSURE

A fluid end assembly disclosed herein comprises a body, an inlet valve, and an outlet valve. The body defines a fluid bore, a plunger bore, and an outlet port. The fluid bore extends through the body between first and second opposite openings. The plunger bore extends partially in the body from a third opening of the body to a closed inner end and intersects the fluid bore. The outlet port communicates with the fluid bore. The inlet valve is disposed toward the first opening of the body and is configured to control fluid communication between the first opening and the fluid bore. The outlet valve is disposed toward the second opening of the body and is configured to control fluid communication between the outlet port and the fluid bore.

The closed inner end can define a concave profile integrally formed into the plunger bore and exposed to the fluid bore.

The second opening can comprise a closure being removable and being configured to seal the fluid bore. The closure can comprise: a sand cap disposed against a shoulder defined in the second opening, the sand cap having a seal engaged with the second opening; and a retainer threaded in the second opening against the sand cap.

The inlet valve can comprise: a seat disposed in the first opening; a stop disposed in the fluid bore adjacent to the seat; a poppet disposed between the seat and the stop; and a spring disposed between the stop and the poppet and biasing the poppet toward the seat. The outlet valve can comprise: a seat disposed in the second opening; a poppet disposed between the seat and the sand cap; and a spring biasing the poppet toward the seat.

The inlet valve can be configured to permit fluid communication from the first opening to the fluid bore in response to a first pressure differential and is configured to restrict fluid communication from the fluid bore to the first opening in response to a second pressure differential, and the outlet valve can be configured to restrict fluid communication from the outlet port to the fluid bore in response to the first pressure differential and is configured to permit fluid communication from the fluid bore to the outlet port in response to the second pressure differential.

The fluid bore can define an outlet pocket toward the second opening and defines an inlet pocket toward the first opening. The outlet pocket can define a second inner dimension being greater than a first inner dimension of the inlet pocket. The inlet valve can have a maximum outer dimension configured to pass through the second inner dimension.

A well service pump disclosed herein comprises a plunger, a fluid end, an inlet valve, and an outlet valve. The plunger is configured to reciprocate back and forth. The fluid end defines a fluid bore, a plunger bore, and an outlet port. The fluid bore extends through the fluid end between first and second opposite openings. The plunger bore extends partially in the fluid end from a third opening of the fluid end to a closed inner end and intersects the fluid bore. The third opening is configured to receive the plunger, and the outlet port communicates with the fluid bore. The inlet valve is disposed toward the first opening of the fluid end and is configured to control fluid communication between the first opening and the fluid bore. The outlet valve is disposed toward the second opening of the fluid end and is configured to control fluid communication between the outlet port and the fluid bore.

The closed inner end can define a concave profile integrally formed into the plunger bore and exposed to the fluid bore.

The second opening can comprise a closure being removable and being configured to seal the fluid bore.

The closure can comprise: a sand cap disposed against a shoulder defined in the second opening, and the sand cap can have a seal engaged with the second opening; and a retainer threaded in the second opening against the sand cap.

The outlet valve can comprise: a seat disposed in the second opening; a poppet disposed between the seat and the sand cap; and a spring biasing the poppet toward the seat. The inlet valve can comprise: a seat disposed in the first opening; a stop disposed in the fluid bore adjacent to the seat; a poppet disposed between the seat and the stop; and a spring disposed between the stop and the poppet and biasing the poppet toward the seat.

The inlet valve can be configured to permit fluid communication from the first opening to the fluid bore in response to a first pressure differential and is configured to restrict fluid communication from the fluid bore to the first opening in response to a second pressure differential; and the outlet valve can be configured to restrict fluid communication from the outlet port to the fluid bore in response to the first pressure differential and is configured to permit fluid communication from the fluid bore to the outlet port in response to the second pressure differential.

A method is disclosed herein of manufacturing a fluid end assembly for a well service pump. The method comprises: forming a fluid bore extending through a body between first and second opposite openings, forming a plunger bore extending partially in the body from a third opening of the body to a closed inner end and intersecting the fluid bore; forming an outlet port communicating with the fluid bore; installing an inlet valve adjacent to the first opening of the body, the inlet valve being configured to control fluid communication between the first opening and the fluid bore; installing an outlet valve adjacent to the second opening of the body, the outlet valve being configured to control fluid communication between the outlet port and the fluid bore; and sealing the fluid bore with a closure disposed in the second opening of the body.

The method can further comprises installing a seal in the third opening of the body, the seal being configured to seal with a reciprocating plunger of the well service pump.

Forming the plunger bore extending partially in the body from the third opening of the body to the closed inner end can comprise forming the closed inner end with a concave profile exposed to the fluid bore.

Installing the inlet valve can comprise: passing an inlet seat of the inlet valve into the fluid bore from the second opening of the body and fitting the inlet seat in the fluid bore adjacent to the first opening of the body; passing a poppet of the inlet valve into the fluid bore from the second opening of the body and disposing the poppet adjacent to the inlet seat; and passing a stop and a spring of the inlet valve into the fluid bore from the second opening of the body and fitting the stop in the fluid bore with the spring disposed between the stop and the poppet.

Installing the outlet valve can occur after installing the inlet valve.

Installing the outlet valve toward the second opening of the body can comprise: passing a seat of the outlet valve into the fluid bore from the second opening of the body and fitting the seat in the fluid bore adjacent to the second opening of the body; passing a poppet of the outlet valve into the fluid bore from the second opening of the body and disposing the poppet adjacent to the seat; passing a spring of the inlet valve into the fluid bore from the second opening of the body and disposing the spring adjacent to the poppet; and fitting the closure in the second opening with the spring disposed between the closure and the poppet.

The foregoing summary is not intended to summarize each potential embodiment or every aspect of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a top view of a well service pump according to the prior art.

FIG. 1B is a side cross-sectional view of the well service pump of FIG. 1A.

FIG. 2 is a cross-sectional view of a conventional fluid end assembly according to the prior art.

FIG. 3 is a partial view of the fluid end assembly of FIG. 2 .

FIG. 4 is a cross-sectional view of a fluid end assembly according to the present disclosure.

FIG. 5 is a partial view of the fluid end assembly of FIG. 4 .

DETAILED DESCRIPTION

FIG. 4 is a cross-sectional view of a fluid end assembly 100 according to the present disclosure. As will be appreciated, the fluid end assembly 100 can be used on a well service pump, such as the quintiplex pump of FIGS. 1A-1B, or with other types of pumps. Accordingly, a well service pump of the present disclosure has plungers 30 configured to reciprocate back and forth. The fluid end assembly 100 is mounted on the well service pump with plunger bores 116 of the assembly 100 configured to receive the plungers 30.

The fluid end assembly 100 includes a body 110, which is typically elongate to accommodate the adjacent plungers 30 of the well surface pump. The body 110 defines fluid bores 112, plunger bores 116, and an outlet port 118. In this cross-sectional view, only one set of bores 112, 116 are shown for one plunger 30, but the body 110 can have more sets of bores 112, 116 arranged laterally therein for the adjacent plungers 30 of the well surface pump.

The fluid bore 112 extends through the body 110 between first and second opposite openings 114 a-b. The plunger bore 116 extends partially in the body 110 from a third opening 114 c of the body 110 to a closed inner end 119. The plunger bore 116 intersects the fluid bore 112 to form a fluid chamber 115. The outlet port 118 communicates with the fluid bore 112. As is typically, the outlet port 118 is defined laterally through the body 110 and connects the several adjacent fluid bores of the assembly 100 together.

As is typical, the fluid end assembly 100 has a multitude of vertical fluid bores 112, each of which has a suction inlet at the first opening 114 a at the bottom and has an opening 114 b at the top of the body 110. Likewise, the fluid end assembly 100 has an equal number of horizontal plunger bores 116, which intersect a corresponding one of the fluid bores 112. As shown, the plunger bore 116 can be perpendicular to fluid bore 112. Similarly, the high-pressure outlet port 118 can be perpendicular to the fluid bores 112 and can interconnect with the multiple fluid bores 112 in the body 110. A suction manifold (not shown) is fixedly attached to the bottom of the fluid end assembly 100 to provide fluid for the suction inlets of the first openings 114 a. Likewise, an output manifold (not shown) is fixedly attached to the fluid end assembly 100 to provide fluid for the outlet port 118.

Internally, an inlet valve 120 is disposed toward the first opening 114 a of the body 110 and is configured to control fluid communication between the first opening 114 a and the fluid bore 112. In this way, the first opening 114 a forms a suction inlet of the body 110 to draw in fluid from an inlet line or piping (not shown). An outlet valve 130 is disposed toward the second opening 114 b of the body 110 and is configured to control fluid communication between the outlet port 118 and the fluid bore 112.

On the body 110, the second opening 114 b is closed and sealed by a closure or discharge cover 140, which seals off the fluid bore 112. This closure 140 is removable, which allows for assembly and servicing of the fluid end assembly 100. As shown, for example, the closure 140 can include a sand cap 142 and a retainer 144. The sand cap 142 is set against a shoulder in the second opening 114 b and has seals to engage the opening 112. The retainer 144 threads into the second opening 114 b against the sand cap 142.

For removal, installation, and service, packing 117 is inserted concentrically into the plunger bore 116. The plunger 30 is inserted into plunger bore 116, and a packing nut is threaded into the plunger bore 116 to hold the plunger packing 117 in place. At the other end of the plunger bore 116, the closed inner end 119 defines a concave or dome profile integrally formed into the end wall of the plunger bore 116. This inner end 119 is exposed to the fluid chamber 115 between the intersecting bores 112, 116.

The concave or dome profile of the closed inner end 119 can define a hemispherical surface, and the profile can be defined by one or more radii R of curvature. The profile can be uniform or non-uniform. In general, the profile of the closed inner end 119 can have a dome shape with an elliptical in profile as shown or can have another shape that helps distribute, disperse, or otherwise spread the forces applied against the surface of the closed end 119.

As shown, the inlet valve 120 can be a check valve or a poppet valve and can be disposed below the fluid chamber 115 as shown. For example, the inlet valve 120 includes a seat 122, a poppet 124, a stop 126, and a spring 128. The seat 122 is concentrically located in a seat pocket 113 a formed into the fluid bore 112 near the inlet opening 114 a. The stop 126 is disposed in the fluid bore 112 adjacent to the seat 122. The stop 126 can be a winged clip or the like that is held in the fluid bore 112. The poppet 124 is disposed between the seat 122 and the stop 126, and the spring 128 positioned between the poppet 124 and stop 126 biases the poppet 124 toward the seat 122.

Similarly, the outlet valve 130 can be a check valve or a poppet valve and can be disposed above the fluid chamber 115 as shown. For example, the outlet valve 130 includes a seat 132, a poppet 134, and a spring 138. The seat 132 is concentrically located in a seat pocket 113 b formed into the fluid bore 112 near the second opening 114 b, and the poppet 134 is disposed between the seat 132 and the sand cap 142. The spring 138 positioned between the poppet 134 and sand cap 142 biases the poppet 134 toward the seat 132.

As the plunger 30 is reciprocated in the plunger bore 116, fluid is moved in the fluid chamber 115, and pressure differentials are produced on the valves 120, 130. The inlet valve 120 is configured to permit fluid communication from the first opening 114 a to the fluid chamber 115 in response to a first pressure differential and is configured to restrict fluid communication from the fluid chamber 115 to the first opening 114 a in response to a second pressure differential. The outlet valve 130 is configured to restrict fluid communication from the outlet port 118 to the fluid chamber 115 in response to the first pressure differential and is configured to permit fluid communication from the fluid chamber 115 to the outlet port 118 in response to the second pressure differential.

During manufacture, the fluid bore 112 is formed in the body 110 to extend through the body 110 between the first and second opposite openings 114 a-b. The plunger bore 116 is formed in the body 110 to extending partially in the body 110 from a back opening 114 c to a closed inner end 119 so that the plunger bore 116 intersects the fluid bore 112 to produce the fluid chamber 115. Meanwhile, the outlet port 118 is formed to communicate with the fluid bore 112 and typically runs laterally along the length of the body 110 to interconnect the multiple fluid bores 112 in the fluid end assembly 100.

Manufacture of the fluid end assembly 100 involves various machining steps, which are generally discussed here and not in any particular order. During manufacture, the fluid bore 112 is formed through the body 110. The seat pockets 113 a-b and threads for the seats 122, 132 are formed in the fluid bore 112. A profile for fitting the stop 126 is formed in the fluid bore 112. Threads and shoulders for the closure 140 are formed at the second opening 114 b. The outlet port 118 is formed laterally through the body 110 to communicate with the fluid bore 112. The plunger bore 116 is formed in the body 110 to have the open end 114 c and the inner closed end 119. Profiles, threads, and the like are formed in the open end 114 c to accommodate the packing 117 and the like. The closed inner end 119 is preferably formed to define a concave profile, which faces the fluid chamber 115 and extends beyond the circumference of the fluid bore 112.

Assembly of the fluid end assembly 100 involves various steps, which are generally discussed here. To allow for assembly, the outlet pocket 113 b toward the second opening 114 a defines a second inner dimension D2 that is larger than a first inner dimension D1 of the inlet pocket 113 a toward the first opening 114 b. This allows components of the valves 120, 130 to be passed through the second opening 114 b. Therefore, the maximum outer dimension of the inlet valve 120 is configured to pass through the inner dimension D2 of the second opening 114 b.

The inlet valve 120 is installed in the fluid bore 112 through the second opening 114 b using a valve seating tool assembly (not shown) and other tools to position the valve's components in the features toward the first opening 114 a. In general, the seat 122 of the inlet valve 120 is passed into the fluid bore 112 from the second opening 114 b of the body 110 and is fit in the seat pocket 113 a adjacent to the first opening 114 a. The poppet 124 of the inlet valve 120 is then passed into the fluid bore 112 from the second opening 114 b and is disposed adjacent to the seat 122. The stop 128 of the inlet valve 120 is then fixed in the fluid bore 112 with the spring 126 disposed between the stop 126 and the poppet 124.

After the inlet valve 120 has been installed, the outlet valve 130 is installed in a number of similar steps. For example, the outlet valve 130 is also installed in the fluid bore 112 through the second opening 114 b using a valve seating tool assembly (not shown) and other tools to position the valve's components in the features toward the second opening 114 b. In general, the seat 132 of the outlet valve 130 is passed into the fluid bore 112 from the second opening 114 b of the body 110 and is fit in the seat pocket 113 b adjacent to the second opening 114 b. The poppet 134 of the outlet valve 130 is then passed into the fluid bore 112 from the second opening 114 b and is disposed adjacent to the seat 132. The spring 138 is positioned against the poppet 134.

The fluid bore 112 is then sealed by installing the closure 140 in the second opening 114 b. The sand cap 142 fits in the opening 114 b against the spring 138. The sand cap 142 sets against a shoulder and seals in the second opening 114.c, and the retainer 144 threads in the second opening 114 b against the sand cap 142. A number of further steps are typically performed to integrate the fluid end assembly 100 with a well service pump. For example, the packing 117 is installed in the back opening 114 b to seal with the plunger 30 when inserted in the back opening 114 c.

During operation, the plunger 30 reciprocates back and forth concentrically within plunger bore 116. When the plunger 30 is moving away from the fluid chamber 115, the inlet valve 120 opens and fluid is drawn into the fluid chamber 115 through suction inlet 112. The poppet 134 of the outlet valve 130 is drawn into the valve seat 132, and the outlet valve 130 is closed. During this state, the high-pressure outlet port 118 cannot communicate with the fluid chamber 115.

As the plunger 30 is then pushed towards the fluid chamber 115, the fluid is displaced under high-pressure. The poppet 124 of the inlet valve 120 seats against the seat 132. This closes the inlet valve 120 so that the fluid chamber 115 cannot communicate with the suction inlet 114 a. However, the outlet valve 130 is opened to allow the pressurized fluid to travel from the fluid chamber 115 into high-pressure outlet port 118.

In forming the plunger bore 116 to extend partially in the body 110 as noted above, the closed inner end 119 is formed with a concave or dome profile exposed to the fluid chamber 115. In particular, FIG. 5 gives a view of the fluid chamber 115, showing the closed inner end 119 in more detail. The concave profile of the closed inner end 119 is formed in such a way that cyclic pressure forces F_(A) from the reciprocating plunger 30 is more evenly distributed perpendicular to the surface of the fluid chamber 115. The profile of the closed inner end 119 allows the cyclic pressure force FA to be distributed evenly across a large cross-sectional surface area of the face 111 of the fluid end's body 110 to produce a more distributed force F_(B). The greater cross-sectional area that receives the distributed force F_(B) in combination with the tensile strength of the material of the fluid end's body 110 creates far stronger face 111 and a far stronger overall fluid end assembly 100.

Details of installing and removing the inlet and outlet valves in the fluid end assembly using a tool are disclosed in the incorporated U.S. application Ser. No. 18/116,247, entitled “Method for Removal of Valve Seats within Fluid End Assembly”.

It is to be understood that the disclosure describes several exemplary embodiments for implementing different features, structures, or functions of the disclosed subject matter. Exemplary embodiments of components, arrangements, and configurations are described below to simplify the present disclosure; however, these exemplary embodiments are provided merely as examples and are not intended to limit the scope of the disclosed subject matter. Additionally, the present disclosure may repeat reference numerals and/or letters in the various exemplary embodiments and across the Figures provided herein. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various exemplary embodiments and/or configurations discussed in the various figures. Moreover, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed interposing the first and second features, such that the first and second features may not be in direct contact. Finally, the exemplary embodiments presented below may be combined in any combination of ways, i.e., any element from one exemplary embodiment may be used in any other exemplary embodiment, without departing from the scope of the disclosure.

Additionally, certain terms are used throughout the following description and claims to refer to particular components. As one skilled in the art will appreciate, various entities may refer to the same component by different names, and as such, the naming convention for the elements described herein is not intended to limit the scope of the disclosed subject matter, unless otherwise specifically defined herein. Further, the naming convention used herein is not intended to distinguish between components that differ in name but not function. Additionally, in the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to.” All numerical values in this disclosure may be exact or approximate values unless otherwise specifically stated. Accordingly, various embodiments of the disclosure may deviate from the numbers, values, and ranges disclosed herein without departing from the intended scope. Furthermore, as it is used in the claims or specification, the term “or” is intended to encompass both exclusive and inclusive cases, i.e., “A or B” is intended to be synonymous with “at least one of A and B,” unless otherwise expressly specified herein.

While the disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and description. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the disclosure to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present disclosure. 

1. A fluid end assembly, comprising: a body defining a fluid bore, a plunger bore, and an outlet port, the fluid bore extending through the body between first and second opposite openings, the plunger bore extending partially in the body from a third opening of the body to a closed inner end and intersecting the fluid bore, the outlet port communicating with the fluid bore; an inlet valve disposed toward the first opening of the body and being configured to control fluid communication between the first opening and the fluid bore; and an outlet valve disposed toward the second opening of the body and being configured to control fluid communication between the outlet port and the fluid bore.
 2. The fluid end assembly of claim 1, wherein the closed inner end defines a concave profile integrally formed into the plunger bore and exposed to the fluid bore.
 3. The fluid end assembly of claim 1, wherein the second opening comprises a closure being removable and being configured to seal the fluid bore.
 4. The fluid end assembly of claim 3, wherein the closure comprises: a sand cap disposed against a shoulder defined in the second opening, the sand cap having a seal engaged with the second opening; and a retainer threaded in the second opening against the sand cap.
 5. The fluid end assembly of claim 4, wherein the outlet valve comprises: a seat disposed in the second opening; a poppet disposed between the seat and the sand cap; and a spring biasing the poppet toward the seat.
 6. The fluid end assembly of claim 1, wherein the inlet valve is configured to permit fluid communication from the first opening to the fluid bore in response to a first pressure differential and is configured to restrict fluid communication from the fluid bore to the first opening in response to a second pressure differential; and wherein the outlet valve is configured to restrict fluid communication from the outlet port to the fluid bore in response to the first pressure differential and is configured to permit fluid communication from the fluid bore to the outlet port in response to the second pressure differential.
 7. The fluid end assembly of claim 1, wherein the inlet valve comprises: a seat disposed in the first opening; a stop disposed in the fluid bore adjacent to the seat; a poppet disposed between the seat and the stop; and a spring disposed between the stop and the poppet and biasing the poppet toward the seat.
 8. The fluid end assembly of claim 1, wherein the fluid bore defines an outlet pocket toward the second opening and defines an inlet pocket toward the first opening, the outlet pocket defining a second inner dimension being greater than a first inner dimension of the inlet pocket, the inlet valve having a maximum outer dimension configured to pass through the second inner dimension.
 9. A well service pump, comprising: a plunger being configured to reciprocate back and forth; a fluid end defining a fluid bore, a plunger bore, and an outlet port, the fluid bore extending through the fluid end between first and second opposite openings, the plunger bore extending partially in the fluid end from a third opening of the fluid end to a closed inner end and intersecting the fluid bore, the third opening being configured to receive the plunger, the outlet port communicating with the fluid bore; an inlet valve disposed toward the first opening of the fluid end and being configured to control fluid communication between the first opening and the fluid bore; and an outlet valve disposed toward the second opening of the fluid end and being configured to control fluid communication between the outlet port and the fluid bore.
 10. The well surface pump of claim 9, wherein the closed inner end defines a concave profile integrally formed into the plunger bore and exposed to the fluid bore.
 11. The well surface pump of claim 9, wherein the second opening comprises a closure being removable and being configured to seal the fluid bore.
 12. The well surface pump of claim 11, wherein the closure comprises: a sand cap disposed against a shoulder defined in the second opening, and the sand cap having a seal engaged with the second opening; and a retainer threaded in the second opening against the sand cap.
 13. The well surface pump of claim 12, wherein the outlet valve comprises: a seat disposed in the second opening; a poppet disposed between the seat and the sand cap; and a spring biasing the poppet toward the seat.
 14. The well surface pump of claim 9, wherein the inlet valve is configured to permit fluid communication from the first opening to the fluid bore in response to a first pressure differential and is configured to restrict fluid communication from the fluid bore to the first opening in response to a second pressure differential; and wherein the outlet valve is configured to restrict fluid communication from the outlet port to the fluid bore in response to the first pressure differential and is configured to permit fluid communication from the fluid bore to the outlet port in response to the second pressure differential.
 15. The well surface pump of claim 9, wherein the inlet valve comprises: a seat disposed in the first opening; a stop disposed in the fluid bore adjacent to the seat; a poppet disposed between the seat and the stop; and a spring disposed between the stop and the poppet and biasing the poppet toward the seat.
 16. A method of manufacturing a fluid end assembly for a well service pump, the method comprising: forming a fluid bore extending through a body between first and second opposite openings, forming a plunger bore extending partially in the body from a third opening of the body to a closed inner end and intersecting the fluid bore; forming an outlet port communicating with the fluid bore; installing an inlet valve adjacent to the first opening of the body, the inlet valve being configured to control fluid communication between the first opening and the fluid bore; installing an outlet valve adjacent to the second opening of the body, the outlet valve being configured to control fluid communication between the outlet port and the fluid bore; and sealing the fluid bore with a closure disposed in the second opening of the body.
 17. The method of claim 16, further comprising installing a seal in the third opening of the body, the seal being configured to seal with a reciprocating plunger of the well service pump.
 18. The method of claim 16, wherein forming the plunger bore extending partially in the body from the third opening of the body to the closed inner end comprises forming the closed inner end with a concave profile exposed to the fluid bore.
 19. The method of claim 16, wherein installing the inlet valve comprises: passing an inlet seat of the inlet valve into the fluid bore from the second opening of the body and fitting the inlet seat in the fluid bore adjacent to the first opening of the body; passing a poppet of the inlet valve into the fluid bore from the second opening of the body and disposing the poppet adjacent to the inlet seat; and passing a stop and a spring of the inlet valve into the fluid bore from the second opening of the body and fitting the stop in the fluid bore with the spring disposed between the stop and the poppet.
 20. The method of claim 16, wherein installing the outlet valve occurs after installing the inlet valve.
 21. The method of claim 16, wherein installing the outlet valve toward the second opening of the body comprises: passing a seat of the outlet valve into the fluid bore from the second opening of the body and fitting the seat in the fluid bore adjacent to the second opening of the body; passing a poppet of the outlet valve into the fluid bore from the second opening of the body and disposing the poppet adjacent to the seat; passing a spring of the inlet valve into the fluid bore from the second opening of the body and disposing the spring adjacent to the poppet; and fitting the closure in the second opening with the spring disposed between the closure and the poppet. 